Memory device with strong polarization coupling

Abstract

A semiconductor memory device and method for providing the semiconductor memory device are described. The semiconductor memory device includes a ferroelectric capacitor. The ferroelectric capacitor includes a first electrode, a second electrode and a multilayer insulator structure between the first and second electrodes. The multilayer insulator structure includes at least one ferroelectric layer and at least one dielectric layer. The at least one ferroelectric layer and the at least one dielectric layer share at least one interface and have a strong polarization coupling.

We claim: 
     
       1. A semiconductor memory device comprising:
 a ferroelectric capacitor including a first electrode, a second electrode and a multilayer insulator structure between the first electrode and the second electrode, the multilayer insulator structure including at least one ferroelectric layer and at least one dielectric layer, the at least one ferroelectric layer and the at least one dielectric layer sharing at least one interface and having a strong polarization coupling, wherein the at least one ferroelectric layer has a first polarization, the at least one dielectric layer has a second polarization, the strong polarization coupling being such that the first polarization and the second polarization are within twenty percent of each other. 
 
     
     
       2. The semiconductor memory device of  claim 1  wherein the first polarization and the second polarization are within ten percent of each other. 
     
     
       3. The semiconductor memory device of  claim 1  wherein the first polarization and the second polarization are within two percent of each other. 
     
     
       4. The semiconductor memory device of  claim 1  wherein the at least one ferroelectric layer includes a first ferroelectric layer, the at least one dielectric layer includes a first dielectric layer, the first ferroelectric layer sharing a first interface of the at least one interface with the first dielectric layer, the multilayer gate insulator structure having an interface polarization coupling constant (λ) that is at least one of greater than the negative one multiplied by α FE  multiplied by t FE  (λ>−α FE *t FE ) and greater than the absolute value of α FE  multiplied by t FE (λ>|α FE |*t FE ) where α FE  is a material parameter of the ferroelectric layer and t FE  is a thickness of the ferroelectric layer. 
     
     
       5. The semiconductor memory device of  claim 1  wherein the at least one ferroelectric layer includes a first ferroelectric layer, the at least one dielectric layer includes a first dielectric layer and a second dielectric layer, the first ferroelectric layer sharing a first interface of the at least one interface with the first dielectric layer, the first ferroelectric layer sharing a second interface of the at least one interface with the second dielectric layer, the multilayer gate insulator structure having a first interface polarization coupling constant (λ 1 ) for the first interface and a second interface polarization coupling constant (λ 2 ) for the second interface such that a sum of the first and second interface polarization constants is at least one of greater than the negative one multiplied by α FE  multiplied by t FE  (λ 1 +λ 2 >−α FE *t FE ) and greater than the absolute value of α FE  multiplied by t FE  (λ 1 +λ 2 >|α FE |*t FE ) where α FE  is a material parameter of the ferroelectric layer and t FE  is a thickness of the ferroelectric layer. 
     
     
       6. The semiconductor memory device of  claim 1  wherein the multilayer insulator structure has a total thickness of the at least one ferroelectric layer (d FE ), a total thickness of the at least one dielectric layer (d DE ), an interface polarization coupling constant (λ), α FE  is a material parameter of the at least one ferroelectric layer and a ferroelectric permeability (χ) such that:
   α DE   d   DE >|α FE   |d   FE λ/(λ−|α FE   |d   FE )
 
 where the total thickness of the at least one ferroelectric layer is a first sum of at least one thickness for each of the at least one ferroelectric layer, the total thickness of the at least one dielectric layer is a second sum of at least one thickness for each of the at least one dielectric layer. 
 
     
     
       7. The semiconductor memory device of  claim 1  wherein the at least one dielectric layer includes at least one of a perovskite oxide, SrTiO 3 , Al 2 O 3 , SiO 2  and SiON and wherein the at least one ferroelectric layer includes at least one of a ferroelectric perovskite, (Pb(Zr—Ti)O 3 ), BaTiO 3 , at least one HfO 2 -based ferroelectric material, Si-doped HfO 2  and ferroelectric (Hf—Zr)O 2 . 
     
     
       8. The semiconductor memory device of  claim 1  wherein the at least one ferroelectric layer is epitaxial to the at least one dielectric layer. 
     
     
       9. The semiconductor memory device of  claim 1  wherein the semiconductor memory device is a dynamic random-access memory cell. 
     
     
       10. The semiconductor memory device of  claim 9  further comprising:
 a selection transistor coupled with the ferroelectric capacitor. 
 
     
     
       11. A semiconductor memory device comprising:
 a ferroelectric capacitor including a first electrode, a second electrode and a multilayer insulator structure between the first electrode and the second electrode, the multilayer insulator structure including at least one ferroelectric layer and at least one dielectric layer, the at least one ferroelectric layer and the at least one dielectric layer sharing at least one interface and having a strong polarization coupling, wherein at least one of the at least one ferroelectric layer has at least one electrical polarization that is free from hysteresis. 
 
     
     
       12. A semiconductor memory device comprising:
 a plurality of memory cells, each of the plurality of memory cells including a ferroelectric capacitor, the ferroelectric capacitor having a first electrode, a second electrode and at least one multilayer insulator structure between the first electrode and the second electrode, the at least one multilayer insulator structure including at least one ferroelectric layer and at least one dielectric layer, the at least one ferroelectric layer and the at least one dielectric layer sharing at least one interface and having a strong polarization coupling, wherein the at least one ferroelectric layer has a first polarization, the at least one dielectric layer has a second polarization, the strong polarization coupling being such that the first polarization and the second polarization are within twenty percent of each other. 
 
     
     
       13. The semiconductor memory device of  claim 12  wherein the first polarization and the second polarization are within ten percent of each other. 
     
     
       14. The semiconductor memory device of  claim 11  wherein the semiconductor device is a dynamic random-access memory (DRAM), the at least one dielectric layer includes at least one of a perovskite oxide, SrTiO 3 , Al 2 O 3 , SiO 2  and SiON, and the at least one ferroelectric layer include at least one of a ferroelectric perovskite, (Pb(Zr—Ti)O 3 ), BaTiO 3 , at least one HfO 2 -based ferroelectric material, Si-doped HfO 2  and ferroelectric (Hf—Zr)O 2 . 
     
     
       15. A semiconductor device comprising:
 a plurality of memory cells, each of the plurality of memory cells including a ferroelectric capacitor, the ferroelectric capacitor having a first electrode, a second electrode and at least one multilayer insulator structure between the first electrode and the second electrode, the at least one multilayer insulator structure including at least one ferroelectric layer and at least one dielectric layer, the at least one ferroelectric layer and the at least one dielectric layer sharing at least one interface and having a strong polarization coupling, wherein the at least one ferroelectric layer is epitaxial to the at least one dielectric layer and has at least one electrical polarization that is free from hysteresis. 
 
     
     
       16. A method for providing a semiconductor device comprising:
 providing a first electrode layer; 
 providing a multilayer insulator structure on the first electrode layer including
 providing at least one ferroelectric layer; and 
 providing at least one dielectric layer such that the at least one ferroelectric layer and the at least one dielectric layer share at least one interface and have a strong polarization coupling, wherein the at least one ferroelectric layer has a first polarization, the at least one dielectric layer has a second polarization, the strong polarization coupling being such that the first polarization and the second polarization are within twenty percent of each other; 
 
 providing a second electrode, the multilayer insulator structure residing between the second electrode and the first electrode. 
 
     
     
       17. The method of  claim 16  wherein the multilayer gate insulator structure has a total thickness of the at least one ferroelectric layer (d FE ), a total thickness of the at least one dielectric layer (d DE ), an interface polarization coupling constant (λ), α FE  is a material parameter of the at least one ferroelectric layer and a ferroelectric permeability (χ) such that:
   α DE   d   DE >|α FE   |d   FE λ/(λ−|α FE   |d   FE )
 
 
       where the total thickness of the at least one ferroelectric layer is a first sum of at least one thickness for each of the at least one ferroelectric layer, the total thickness of the at least one dielectric layer is a second sum of at least one thickness for each of the at least one dielectric layer. 
     
     
       18. The semiconductor device of  claim 1 , wherein a ferroelectric layer of at least one ferroelectric layer and a dielectric layer of the at least one dielectric layer share an interface and have a combined thickness of at least five nanometers and not more than thirty nanometers, the dielectric layer having a thickness of at least 1.5 nm and not more than six nanometers. 
     
     
       19. The semiconductor device of  claim 12 , wherein a ferroelectric layer of at least one ferroelectric layer and a dielectric layer of the at least one dielectric layer share an interface and have a combined thickness of at least five nanometers and not more than thirty nanometers, the dielectric layer having a thickness of at least 1.5 nm and not more than six nanometers. 
     
     
       20. The method device of  claim 16 , wherein a ferroelectric layer of at least one ferroelectric layer and a dielectric layer of the at least one dielectric layer share an interface and have a combined thickness of at least five nanometers and not more than thirty nanometers, the dielectric layer having a thickness of at least 1.5 nm and not more than six nanometers.